Method and apparatus for automated coverslipping

ABSTRACT

An apparatus and method for selecting and dispensing coverglasses over specimens on slides for the purpose of viewing specimens through a microscope. The selecting device contains a suctioning mechanism for picking up a coverglass from a stack of coverglasses. It also contains the ability to bend the coverglass to assist in separating the coverglasses. The apparatus further contains a matched barrier to eliminate any coverglasses that may stick to the selected coverglass. The selecting device also contains spring members which aid in the dispensing of the coverglass. After the suctioning mechanism releases the coverglass, the spring members exert a force onto the coverglass to insure that it is released from the selecting device and placed onto the slide. After placement of the coverglass onto the slide, capillary action pushes air bubbles out from underneath the coverglass.

This is a divisional of U.S. patent application Ser. No. 10/424,335,filed Apr. 25, 2003, now U.S. Pat. No. 7,271,006 which claims thebenefit of U.S. Provisional Patent Application No. 60/375,925, filed onApr. 26, 2002, the contents of which applications are incorporated byreference herein.

FIELD OF THE INVENTION

This invention relates to a method and apparatus for automaticallycovering a specimen to be examined on a microscope slide with a tissuecoverglass.

BACKGROUND OF THE INVENTION

Scientists examine numerous specimens placed on slides usingmicroscopes. Typically, a specimen is covered with a thin transparentcoverglass. This is done for several reasons. The coverglass can flattenthe specimen so that the specimen is in the same viewing plane, therebyallowing one to view the specimen better. The coverglass providesprotection for the specimen from the objective lens of the microscopeshould the lens be placed too closely to the slide. The coverglass mayfurther provide a housing structure or an area by which the specimenwill be permanently retained on the slide. The coverglass, incombination with a liquid adhesive, also helps to preserve the specimenfor archiving purposes.

The coverglass is typically a thin, rectangular, square or round pieceof glass or plastic which is placed in direct contact with and over thespecimen on the slide. The coverglass comes in a variety of sizes andshapes. One example of the coverglass has dimensions of about 1″×2″ and0.005″ to 0.009″ thick. They are packaged stacked in a vertical pile.This stacking presents a problem: the coverglasses are difficult tohandle and separately remove from the stack since they are fragile andmay stick together easily. Typically, to remove one coverglass from thestack, a considerable amount of bending moment is applied at the middleof the coverglass. For example, some prior art systems, such as shown inU.S. Pat. No. 5,989,386 (Elliott) use two suction cup devices on acoverglass, placed on both sides of the middle of the coverglass. Thesuction cups thereafter bend the coverglass, creating great stress inthe middle of the coverglass in order to separate the coverglass fromthe stack of coverglasses. However, this action results in numerouscoverglasses breaking because they are very fragile and the forceapplied was greater than the stability of the glass. The bending forcecauses a disproportionate amount of stress at the center of thecoverglass. Furthermore, the bending action did not guarantee that onlyone coverglass was selected.

After selecting a single coverglass, the coverglass is then placed overthe specimen on a slide in the presence of a liquid adhesive. Thispresents other problems. For example, it is important that there are noair bubbles trapped under the coverglass when it is placed onto theslide. Also, it is important not to harm the specimen in any way whenpositioning the coverglass onto the slide. One way to apply thecoverglass was to place the coverglass on the slide, and then applypressure onto the coverglass compress to remove trapped air bubbles. Inaddition, handling and separating the coverglasses at times can chargethem with static electricity. Electrostatic forces can hold thecoverglass to the suction cups even after turning the mechanism off,making it difficult to apply the coverglass to the slide. Moreover, thecompression of the coverglass to remove air bubbles may cause theadhesive on the tissue sample to expel outward, thereby potentiallycontaminating other slides or other portions of the machine.

Thus, there exists a need to provide a better automated coverslipperthat avoids the problems of prior art automated coverslippers.

SUMMARY OF THE INVENTION

In one embodiment, the invention is directed to a method and apparatusfor removing at least one coverglass from a stack of coverglasses. Inone aspect, the method and apparatus removes the coverglass using asingle sealing member. The sealing member forms a seal along acircumference of the coverglass (e.g., providing a seal along orproximate to the edges of the coverglass). The coverglass may then bebent using the single sealing member. The bending may include deformingthe coverglass so that the coverglass has a constant or near constantbend radius (i.e., the curvature of the coverglass is approximatelyconstant along the edge, preferably the longitudinal edge, of thecoverglass). In one embodiment, the bending of the coverglass isperformed using the sealing member in combination with a suction block.The suction block may be used as a support for the coverglass duringdeformation and may be shaped with a constant curvature so that when thecoverglass is deformed, its shape has a constant (or substantiallyconstant) bend radius. Greater separating force is generated along theedges while not overstressing other areas, which is less likely to breakthe coverglass and more likely to result in a separation of thecoverglass. In this manner, the apparatus and method enable theseparation of a coverglass from the stack of coverglasses. Afterselection of a coverglass, the stack of remaining coverglasses may belowered and a curved barrier that may be matched to the shape of thebent coverglass wipes beneath the selecting device to remove anyclinging coverglasses that may be present. Any coverglasses wiped frombeneath the selected one will be placed back onto the remaining stack.

Another embodiment is an automatic device and method for dispensing thecoverglass onto the slide after the coverglass has been successfullyremoved from the stack. In one aspect, a liquid for adhering thecoverglass is applied along an edge of the slide. In a first preferredembodiment, the liquid is an adhesive-activating liquid such as xyleneor toluene, that functions to dissolve a pre-applied layer of adhesiveon the coverslip. In a second preferred embodiment, the liquid is itselfan adhesive, and is applied to a standard coverslip. The liquid may bein the form of drops or a continuous bead. An edge of the coverglass isthen released (e.g., placed, via gravity) at an edge of the specimen(preferably at the long end of the slide) proximate to the liquidpreviously placed on the slide. Thus, the cover glass and the surface ofthe slide may form a “V” shape. In one embodiment, while one edge of thecoverglass is touching the slide, the opposite edge is lowered (thoughnot to the point where the opposite edge touches the slide). Thereafter,the remaining edge of the coverglass is released, allowing it to settleonto the sample tissue on the slide. In this manner, there is acontinuous bead of fluid at the intersection between the coverglass andthe slide.

In the embodiment wherein the coverglass is held via a suctioningmechanism, the suctioning mechanism is turned off allowing thecoverglass to fall onto the slide via gravity. Spring member(s) may belocated in the flexible backing plate. The spring member(s), compressedby the force of the coverglass against the flexible backing plate, exerta small restoring force on the coverglass when it is released insuringthe disengagement of the coverglass from the sealing member. Moreover,the coverglass may be held by a conductive sealing member. In thismanner, the sealing member may be connected to ground, thereby reducingthe possibility of static electricity causing the coverglass to clingafter the suctioning mechanism is turned off.

Still another aspect of the invention is a cartridge for a stack ofcoverglasses. The cartridge may comprise an open-ended substantiallyrectangular box, the open end being substantially concave along at leastone of its long axes, one or more alignment lips for aligning and thenguiding the cartridge into position, one or more detents for locatingone or more plungers thereby securing the cartridge in place, and one ormore apertures in the bottom end of the box for allowing entry of a forkto push the coverglasses into position. The alignment lip may be locatedadjacent to the closed end of the box. Moreover, the detents may belocated on the alignment lip. In addition, the cartridge may comprise atouch memory button. Further, the cartridge may comprise at least onecutout, the cutout being located in an interior of the rectangular boxwhere two of the sidewalls meet.

These as well as other features and advantages of the present inventionwill become apparent to those of ordinary skill in the art by readingthe following detailed description, with appropriate reference to theaccompanying drawings.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a frontal perspective view of the automated coverslipperapparatus.

FIG. 2 is a block diagram of the automated coverslipper apparatus.

FIG. 3 is a perspective view of the head portion of the automatedcoverslipper of FIG. 1.

FIG. 4 is a perspective view of one embodiment of the support block andsealing member assembly shown in FIG. 3.

FIG. 5 is a bottom perspective view of the sealing member assemblyshowing shown in FIG. 4.

FIG. 6 is a perspective view of the cartridge, cartridge holder, andtuning fork, lead screw, shaft, belt and motor.

FIG. 7 is a perspective view of the cartridge supply and dispense deviceof FIG. 1.

FIG. 8 a is a top perspective view of the cartridge of FIG. 6.

FIG. 8 b is a bottom perspective view of the cartridge of FIG. 6.

FIG. 9 a is a top perspective view of a tray with vertebrae structureslide holders and slides.

FIG. 9 b is a partially exploded view of the tray in FIG. 9 a.

FIG. 9 c is an individual section of the vertebrae structure slideholder.

FIGS. 10 a-10 b are a flow chart of the steps of separating anddispensing a coverglass.

FIGS. 11 a-11 d show a method of separating coverglasses.

FIGS. 12 a-12 c show schematics depicting a method of dispensing acoverglass onto a slide.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to FIG. 1, there is shown a perspective view of an automatedcoverslipper module 18. The automated coverslipper module 18 includes ahead portion 20 (see e.g. FIG. 3), a cartridge supply and dispensedevice 22 (see e.g., FIG. 7), and a flat portion 24 upon which a tray 26(see e.g., FIG. 9) sits. The head portion 20 moves in one directionusing motor 28 to move along rail 30.

Referring to FIG. 2, there is shown a block diagram of the automatedcoverslipper module 18. The automated coverslipper module includesinputs/outputs 32, 34. In one embodiment, the automated coverslippermodule is integral with other components of a tissue staining instrument(i.e., contained within a single device). See U.S. Patent ApplicationNo. 60/372,506 filed on Apr. 15, 2002 and incorporated by reference inits entirety. In an alternative embodiment, the automated coverslippermodule may be a physically separate, yet electronically connecteddevice, interacting with other modules of a tissue staining instrument.Examples of tissue staining machines are disclosed in U.S. Pat. No.6,045,759 and U.S. Pat. No. 6,296,809, both of which are herebyincorporated by reference in their entirety.

The inputs 32 and outputs 34, which are discussed below, may communicatewith a central processor (not shown) of the automated tissue stainingmachine. Examples of inputs include control of motors, such as motor 28in FIG. 1 (for moving head assembly in the x-direction), motor 46 inFIG. 3 (for moving the head assembly in the z-direction) and motor 92 inFIG. 6 (for moving the stack of coverglasses upward and downward), eachdescribed subsequently. Examples of outputs include (1) an indication ofthe dispensing of liquid onto the slide (e.g., glue and/or solvent(s));(2) an indication of pumping of the liquid; (3) an indication whether avacuum is achieved; and (4) an indication that the sealing memberassembly (see e.g., FIGS. 4 and 5) is flexed or twisted.

The automated coverslipper module includes a processor 36 and memorydevice 38. As described in more detail below, the automated coverslippermodule 18 further includes motors 40 (such as 28 and 46, shown in FIGS.1 and 3), valves 42 (such as for controlling the dispense of the liquidthrough nozzles 54, shown in FIG. 3), vacuum pump 43 and sensors 44(such as sensors shown in FIGS. 7 and 9). The processor 36 may be amicroprocessor executing commands either received directly from theinputs/outputs or stored in the memory device. The memory device 38 mayinclude either a permanent memory device (such as a read only memory), atemporary storage device (such as a random access memory) or acombination of both. In one embodiment, the memory device 38 may containinstructions for operating the automated coverslipper module 18, theinstructions being sent by the input 32 and temporarily stored in thememory device 38. Alternatively, the memory device 38 may permanentlystore the instructions for operation of the motors 40, valves 42, andsensors 44 with the processor 36 accessing the instructions. This andother arrangements described herein are shown for purposes ofillustration only, and those skilled in the art will appreciate thatother arrangements and other elements (e.g., types of processor, memorydevices, inputs, outputs, etc., whether or not separately known in theprior art) can be used instead, and some elements may be omittedaltogether.

Referring to FIG. 3, there is shown a perspective view of the headportion of the automated coverslipper module. The head portion 20includes dual head assemblies, one for each side of the tray 26 (asshown in FIG. 9). The head portion 20 may include a single head assemblyor multiple head assemblies, depending on the needs of a particularsystem. Further, the head assembly may be moved within the automatedcoverslipper module 18. In one embodiment, the head assembly may bemoved in two directions: the x-direction (by motor 28, as discussedabove); and the z-direction (by motor 46). In an alternate embodiment,the head assembly may be moved in the x-, y-, and z-directions.

The head assembly includes: (1) a sealing member assembly 48 (see e.g.,FIGS. 4 and 5); (2) a support block 50 (see e.g., FIG. 4); (3) at leastone spacer arm 52, and preferably two spacer arms; (4) at least onenozzle 54 for dispensing fluid and associated tubing and valves; (4)device for moving the sealing member assembly 56; and (5) a motor 46. Asshown in FIG. 3, there is a plurality of nozzles 54 for dispensingliquid. In one aspect, the nozzles dispense approximately 50 μL ofliquid. However, more or less fluid may be dispensed. The nozzles 54 maybe composed of a variety of materials depending on the fluid beingdispensed. In one aspect, the liquid dispensed is mounting media (e.g.,a combination of glue and a solvent such as xylene). In another aspect,the liquid dispensed is a solvent such as xylene. In a preferredembodiment, the nozzles 54 are composed of stainless steel with an outerdiameter of Teflon® coating. The nozzles are connected to a liquidcontainer via tubing (not shown) and at least one valve 42 in FIG. 2.The transfer of liquid to the nozzles 54 is controlled by processor 36which controls the least one valve 42.

In one embodiment, the valve 42 includes a “suck back” feature. Nozzles54 may, after dispensing of liquid, include a hanging drop. This hangingdrop is unwanted since it may fall onto one of the samples on theslides. In order to remove the hanging drop, a “suck back” feature isemployed. The “suck back” feature, in operation, reverses the flow ofthe liquid, thereby pulling excess fluid back into nozzles 54. The “suckback” feature may be implemented in a variety of ways. One example is byusing a membrane which is connected to the tubing supplying liquid tonozzles 54. An air cylinder may activate the membrane in order to pull ahanging drop from nozzles 54. A commercially available membrane is soldby SMC Corporation, model number LV23-2S06. Another example is by usinga secondary pump to pump the hanging drop from the edge of nozzles 54.Still another example is by modifying valve 42. In one embodiment, thevalve 42 is a one-way solenoid valve, so that liquid flows from thecontainer to the nozzles. The solenoid valve may be replaced with atwo-way valve so that the valve may send fluid to the nozzles 54 andalso pull fluid from the nozzles 54. The amount of fluid which may bepulled from the nozzles is a small amount, typically no more than a fewdrops to account for any drops hanging on nozzles.

The device 56 for moving the sealing member assembly is, in oneembodiment, an air cylinder. The air cylinder moves the sealing memberassembly 48, and in particular the brackets 66. As disclosedsubsequently with respect to FIG. 4, the brackets 66 may be moved upwardin order to separate a coverglass from the stack of coverglasses.

Referring to FIG. 4, there is shown a perspective view of the coverslipgripper assembly 47 comprising the support block 50 and sealing memberassembly 48 for the head portion 20 (shown in FIG. 3). Support block 50may be composed of a variety of shapes. As shown in the embodiment ofFIG. 4, support block 50 is of rectangular shape having the inner part58 removed to allow space for the tubing 60 (or other conduit) of thevacuum generator 43 to be inserted. In an alternative embodiment, aconduit comprising a cylindrical hole may be drilled or otherwise formedinto the support block for communication of vacuum. The support block 50may be made from machinable polymer, ceramic or metal materials. Acomplete seal, air tight connection should be made between thecoverglass and the sealing member 72 (shown in FIG. 5). The lowerportion 62 of support block 50 is of a curved shape. In a preferredembodiment, the curved shape is a constant (or nearly constant) radius.As discussed subsequently, the flexible backing plate 64 of the sealingmember assembly (while holding a coverglass 68) is bent to conform tothe lower portion 62 of support block 50.

Referring to FIG. 5, there is shown the sealing member assembly 48 whichincludes flexible backing plate 64 and brackets 66. The sealing memberassembly 48 may be mounted to support block 50 either via the flexiblebacking plate 64 (e.g. to the lower portion of support block) or by thebrackets 66 positioned on each side of the support block 50. Thebrackets 66 include holes 70 for connection. The brackets 66 may be madefrom metal materials or they may be made from the same materials as theflexible backing plate 64. In the preferred embodiment, the brackets 66and the flexible backing plate 64 are one integral piece with noconnections between them. In an alternative embodiment, the brackets 66and the flexible backing plate 64 comprise separate pieces connectedtogether. The coverglass 68 is selected and held by flexible backingplate 64, as described in more detail subsequently.

A second preferred embodiment of the coverslip gripper comprises acombination of the sealing member assembly 48 and the support block 50.The major components, i.e., support block 50, flexible backing plate 64,brackets 66, and sealing member 72 may be manufactured as one articlethrough processes well-known in the art, such as injection molding. Thecoverslip gripper would then also have the function of the sealingmember 72 as the sealing member would be integral with the flexiblebacking plate 64.

A bottom view of the sealing member assembly is shown in FIG. 5.Connected underneath the flexible backing plate 64 is a sealing member72. The sealing member 72, in the most preferred embodiment, iselastomeric and may be compressed upon contact with coverglass 68. Thesealing member 72 may also be composed of other materials, such as asoft plastic. The sealing member 72 may be less than 0.25″ thick. Theflexible backing plate 64 may be a flexible material (such as sheetmetal stainless steel backing) that the elastomeric sealing member 72 isbonded to. In a preferred embodiment, the flexible backing plate 64 isrectangular shaped with size comparable to the coverglass 68. Thesealing member 72 may be of any shape which covers the geometric centerof the coverglass, but preferably covers at or proximate to theperimeter of the coverglass. As described subsequently, the sealingmember 72 allows for an evenly distributed force to a perimeter of thecoverglass. In the most preferred embodiment, conductive material may beused for the sealing member 72 which is adhered or affixed to flexiblebacking plate 64. Sealing member 72 may then be grounded, either byconnection to the flexible backing plate 64 or connection directly toground to eliminate static electricity buildup on the sealing member 72.Adding carbon or other conductive materials to the rubber mixture of thesealing member 72 will make it conductive which can then be grounded,solving the problem of electrostatic charge buildup since the sealingmember 72 will discharge the static charge. This may reduce thepossibility of the selected coverglass 68 from adhering to the flexiblebacking plate 64 after dispensing of the coverglass 68. This also mayreduce the possibility of a second coverglass adhering to the selectedcoverglass 68. The sealing member 72 is positioned proximate to theedges of the flexible backing plate 64. For a rectangular flexiblebacking plate 64, the sealing member 72 is of rectangular shape withrounded corners.

Supports 74 of the sealing system are mounted inside the perimeter ofthe sealing member 72 underneath the flexible backing plate 64. In apreferred embodiment, the supports 74 extend nearly to each distal endof the sealing member 72. The preferred embodiment places two supportsspaced equally inside the perimeter of the sealing member 72.Alternative embodiments may use more or less supports of varying lengthsplaced within the sealing member 72. The supports 74 provide rigidityand minimize the deformation of the coverglass 68 when suctioning istaking place. This reduces “cupping” of the coverglass which may produceair bubbles after placing the coverglass on the specimen. The supports74 also provide a firm structure against which the coverglass 68 maymaintain its original form except for the axis of bending. Moreover, thesupports 74 provide rigidity for the coverglass 68 that is selected fromthe stack 182. The supports 74 may be made of the same elastomericmaterial of which the sealing member 72 is made.

Sealing member 72 may provide a complete seal around the top coverglass68 allowing the vacuum pump 43 to produce an equal force to the wholearea of the coverglass 68 when suctioning it from the stack 182. Oneembodiment of the positioning of the vacuum passage 78 may be in thecenter of the flexible backing plate 64 as shown in FIG. 5. The vacuumpassage 78 may be a single, small round shape. Alternatively, the vacuumpassage 78 may be a series of holes all connected to vacuum.

Referring to FIG. 6, there is shown a perspective view of the cartridge80, cartridge holder 82, and fork 84, lead screw 86, shaft 88, belt 90and motor 92. A stack of coverglasses (not shown) is contained withincartridge 80. Further, the cartridge 80 is held within cartridge holder82. The cartridge holder acts to secure the cartridge in at least onedirection. In one embodiment, the cartridge 80 has at least onealignment lip 94 (and preferably two lips, as shown in FIGS. 6, 8 a and8 b) for insertion in at least one slot 96 (and preferably two slots, asshown in FIG. 6). Further, the cartridge holder 82 may include a plunger98 in one or both sides of the cartridge holder in order to engage atleast one slot (and preferably two slots, see FIG. 8 a). The cartridgeholder 82 thus may serve as an x-y-z orienting device.

The coverglasses should contact the sealing member assembly 48, eitherby moving the sealing member assembly 48 to the coverglasses, by movingthe coverglasses to the sealing member assembly 48, or a combination ofboth. In one embodiment, the coverglasses in the cartridge holder 80 areraised a fixed amount to the sealing member 72 so that the topcoverglass may be selected. A motor 92, belt 90, shaft 88, lead screw 86and fork 84 are shown in FIG. 6 for moving the fork upward and downward.The fork, upon being raised, is inserted into slotted holes 118 (shownin FIG. 8 b) in a bottom portion of the cartridge 80. The fork 84, uponentry into the cartridge 80, raises the stack of coverglasses. The motor92 moves the fork 84 upward until the top coverglass contacts thesuction sup assembly 48. The motor 92 thereafter stalls. After apredetermined time, the motor 92 is reversed and the fork 84 is moveddownward, thereby moving the stack of coverglasses.

Referring to FIG. 7, there is shown a perspective view of the cartridgesupply and dispense device 22. Cartridges 80 are fed via a conveyer 100and are placed within channel 102. Motor 108 is used to rotate conveyor100 so that cartridges are lined up against stop 110, as shown in FIG.7. In the embodiment shown in FIG. 3 with two head assemblies, there aretwo stations 107 in which the cartridges 80 are placed. At each station107, the cartridges may be held by cartridge holder 82, as discussedpreviously. When a cartridge in the cartridge holder 82 needs to bemoved, as discussed subsequently, piston 104 is used. Piston 104 pushesa cartridge on conveyor 100 which in turn pushes the cartridge in thecartridge holder 82 onto conveyor 106 for disposal. Conveyor 106 maythen be moved to dispose of cartridge. In one embodiment, a single motor(for example, motor 108) may operate both conveyor 100 and conveyor 106via a cam (not shown) linking the conveyors 100 and 106. Alternatively,conveyor 100 and conveyor 106 may be operated using separate motors.

In order to determine if a cartridge should be placed on conveyor 100,sensor 112 may be placed proximate to conveyor 100. Sensor 112 may be anoptical sensor for sensing if a cartridge is adjacent or proximate tosensor 112. If the sensor 112 senses that no cartridge is present,processor 36 is notified and a message is sent via output 34 to notifyoperator to place cartridges onto conveyor 100.

Typically, a cartridge is used until it is believed to be empty ofcoverglasses or until it is determined that the coverglasses in thecartridge are damaged. In one embodiment, to determine when to replace acartridge, the sealing member assembly 48 is used. During ordinaryoperation, motor 92 moves the stack of coverglasses so that the topcoverglass contacts the flexible backing plate 72. After contact with acoverglass and after turning on the suction pump, a vacuum seal shouldbe formed. This seal may be sensed by sensor 44. In the event thatsensor 44 does not sense that a seal has formed, the processor 36 isnotified. Failure to seal may indicate either that the cartridge isempty of coverglasses or that the coverglasses (either attached toflexible backing plate 72 or on top of the stack) are broken or damaged.The processor commands the motor 92 to lower the stack of coverglasses.Motors 28 and 46 move the head assembly to a place where the tray 26 isnot below and remove the vacuum from the sealing member assembly. Inthis manner, if a damaged coverglass is clinging to the sealing memberassembly 48, it may be removed without falling onto, and subsequentlydamaging, any tissue samples. Motors 28 and 46 thereafter move the headassembly back into position so that motor 92 may raise the stack ofcoverglasses to contact the flexible backing plate 72. If a vacuum sealmay not be generated yet again, this process of moving the head assemblyusing motors 28 and 46 to a predetermined position and removing thevacuum from the sealing member assembly 48 may be repeated again.

In a second preferred embodiment cartridge 80 has a self-containedread-write memory device attached to it for keeping track of datarelated to the cartridge. The memory device may be a “touch memory”device such as an EPROM sold by Dallas Semiconductor as the DS1985 F5 16Kbit add-only touch memory device. Other memory devices may be used tostore the information and allow the end user to retrieve theinformation, such as an RFID (Tag-It HF-I Transponder Inlay Rectangle,Texas Instruments, Dallas, Tex.). As shown in FIG. 8 b, the touch memorydevice 119 is incorporated into the cartridge 80 and containsinformation pertaining to the contents of the cartridge, such as thenumber of coverslips remaining, type, lot number, expiration, andrelated information. The memory device enables communication between thecartridge and the system processor, thus adding an element ofintelligence to the overall system. The data feature includes memorydevice 119 mounted on the cartridge at a position that will notinterfere with coverslip loading and unloading operations of theapparatus, an on-board PIC microcontroller contained within theautomated coverslipper for running the operations of the device whilebeing in communication with the memory device, and a contact reader forthe data button. A similar memory device is described in U.S. Ser. No.08/995,052, filed Dec. 19, 1997, incorporated herein by reference in itsentirety. Its primary function is to initialize the system for each newcoverslip cartridge that is presented to the automated coverslipper, andto keep track of the number remaining. The memory device containsinformation such as the number of coverslips, whether they are pre-gluedor not, date of expiration, lot no., etc. In operation, the memorydevice is initially read-in the number of coverslips in the cartridgewhen loaded with coverslips at the factory. When the cartridge is loadedinto feed position on the coverslipper, contacts (not shown) on thecartridge holder 82 contact the memory device, or the memory device 119itself makes direct electrical contact with a memory reader (not shown)which is built into the upper stage so that as the cartridge is slidinto position it contacts the memory reader. The microcontroller thentracks the number of coverslips left in the cartridge until thecartridge is empty. The on-board microcontroller will then notify theuser through an interface as to how many coverslips are left. Theon-board microcontroller writes the number of coverslips to the memoryafter each dispense step so that in the event of a power loss orinstrument shutdown, the total number of coverslips remaining in thatparticular cartridge is not lost.

Referring to FIGS. 8 a and 8 b, there are shown are a top perspectiveview and bottom perspective view (respectively) of the cartridge of FIG.6. The cartridge includes: an open-ended box with a bottom 120 andsidewalls 122. The bottom 120 and sidewalls 122 form an interior 114. Ina preferred embodiment, the open-ended box is rectangular in shape. Thisrectangular shape is so that the box may house the coverglasses, whichare typically rectangular in shape. However, the cartridge 80 may be ofany shape in which to house the coverglasses.

The cartridge further includes one or more alignment lips 94. Thealignment lip 94 may be on one or more sides of the bottom 120 of thecartridge 80. As shown in FIGS. 8 a and 8 b, there are two alignmentlips, each located adjacent to the closed end of the box. The alignmentlip 94 may be used in conjunction with slot 96, as discussed above, toengage the cartridge 80 into cartridge holder 82. The alignment lip 94may include at least one narrower portion 124. As shown in FIGS. 8 a and8 b, the narrower portions 124 are at the edges of alignment lip 94. Thenarrow portions 124 facilitate entry of the alignment lip 94 into slot96. In addition, the alignment lip 94 may include at least one detent126. The detent 126 may be placed at any portion of the alignment lip94. In a preferred embodiment, the detent 126 is placed in the center ofalignment lip 94, as shown in FIG. 8 a. As discussed previously, detent126 engages plunger 98 of cartridge holder 82.

The cartridge 80 further may include one or more apertures in thebottom. The one or more apertures in the bottom end of the box forallowing entry of a fork to push the coverglasses into position. In apreferred embodiment, the bottom 120 includes two apertures which areoblong in shape. In this manner, fork 84 may enter bottom 120 in orderto raise the stack of coverglasses contained in interior 114 ofcartridge 80.

In addition, the open end of the cartridge 80 may be substantiallyconcave or curved along one of its axis. In a preferred embodiment, theopen end of the cartridge is curved along its long axis. Specifically,as shown in FIGS. 8 a and 8 b, two of the sidewalls 122 have a curved orconcave upper surface 128. As discussed subsequently in FIGS. 11 a-d,the curved upper surface 128 acts as a matched curved barrier for thecoverglass thereby bumping against any clinging coverglasses.

Further, there is at least one cutout 116 along at least a portion ofwhere the sidewalls 122 of the cartridge meet. In a preferredembodiment, as shown in FIG. 8 a, the cutouts 116 are along the entireintersection where the sidewalls 122 meet (i.e., at each of the cornersof interior 114. The cutouts may be of any shape. In one embodiment, thecutouts 116 are curved in shape. The cutouts 116 allow the edges of thecoverglass to be protected from shattering. Typically, the edges of thecoverglasses are prone to breakage. Because of the cutouts 116, theedges of the coverglasses to not touch the sidewalls 122, therebyreducing the possibility of cracking at the edges.

Referring to FIG. 9 a, there is shown a top perspective view of a traywith slide holders and slides. FIG. 9 b is a partially exploded view ofthe tray in FIG. 9 a. As shown in FIG. 9 b, the slides are held in thetray 26 by a vertebrae structure 129. The vertebrae structure 129, in apreferred embodiment, have individual sections to hold each of theslides. In one embodiment, the individual section (shown in perspectiveview in FIG. 9 c) of the vertebrae structure includes a main post 130, astationary side post 132, a clip 134, a spring 136 and teeth 138. Thestationary side post 132, clip 134, spring 136 and teeth 138 may beattached or integral with the main post. In one embodiment, some or allof the vertebrae structure 129 is manufactured by injection molding.Alternatively, some or all of the vertebrae structure 129 are composedof pieces connected or attached to the main post 130.

The clip 134 and the spring 136 work in conjunction to stabilize theslide and to seat an edge of the slide against the stationary post 132.Specifically, an edge of the slide (in a preferred embodiment, thelongitudinal edge) is pushed by the spring so that an opposite edge ispushed against a surface 140 of the stationary post. The teeth 138 maybe rectangular in cross section and may be placed such that, when theslide is inserted, at least one of the teeth abut a top surface of theslide and at least one of the teeth abut a bottom surface of the slide.Therefore, when the slide is inserted into the vertebrae structure, theslide is held securely.

The main post is placed inside tray 26. In one embodiment, the main postincludes side arms 142 that engage feet 144, which may be attached to orintegral with the tray. The side arms 142 are placed so that two edgesof the side arms may be supported by the feet 144. The tray 26 furtherincludes supports 146 which support a bottom side of the slide.

Referring to FIGS. 10 a-10 b, there is shown a flow chart of the stepsof separating and dispensing a coverglass. The coverglass applicationroutine is accessed, as shown at block 150. As discussed previously, thecoverglass application routine may be accessed from memory 38 of theautomated coverslipper module 18. The coverglass application routine maybe placed in memory 38 either by downloading the routine from a hostcomputer or by permanently (or semi-permanently) storing the routine inmemory 38. The liquid for applying to the coverglasses is primed, asshown at block 152. In the embodiment where the head portion 20 includesdual head assemblies, there are liquid valves and associated tubingconnecting the container of liquid to the nozzles 54 for each of thehead assemblies. Priming of each of the head assemblies is performedseparately by turning on the valve of the first head assembly andturning off the valve of the second head assembly being turned off,waiting a predetermined time, turning off the valve of the first headassembly and turning off the valve of the second head assembly beingturned on, waiting a predetermined time, and turning off the valve ofthe second head assembly being turned off.

The head assembly is moved to the home position, as shown at block 154.Typically, motors 28 and 46 are used to move the head portion 20 to apredetermined position. In one embodiment, the head portion 20 is thenmoved from the home position to a position above cartridge 80 whichcontains the stack of coverglasses. In an alternative embodiment, thehome position of the head assembly 20 is in a position above cartridge80. The stack of coverglasses is then moved upward by motor 92 untilcontact with the flexible backing plate, as shown at block 158. Thevacuum pump 43 is turned on, as shown at block 156. Processor 36 of theautomated coverslipper module 18 may then wait a predetermined amount oftime, as shown at block 160. The stack of coverglasses is then moveddownward by motor 92, as shown at block 162. In one embodiment, thestack is moved downward approximately 1/10 of an inch. The flexiblebacking plate 64 is bent, thereby flexing the coverglass held by theflexible backing plate 64 (shown visually in FIG. 11 b), as shown atblock 164. The support block 50, while the flexible backing plate 64 isflexed, is then moved past curved upper surface 128 of cartridge 80(shown visually in FIGS. 11 c-d), as shown at block 166.

The coverglass is then dispensed onto the slide. As shown at block 168,the head assembly is moved into position for dispense of liquid. Theliquid is then dispensed onto the slide, as shown at block 170. The headassembly is then moved into position for dispense of the coverglassattached to flexible backing plate 64, as shown at block 172.Alternatively, the position of the head assembly for dispensing ofliquid and dispensing of the coverglass may be the same, obviating theneed for moving the head assembly after the dispense of liquid. Thevacuum pump 43 is turned off, as shown at block 174. This causes atleast a portion of the coverglass to fall, by gravity, onto the slide.In one embodiment, one edge of the coverglass falls onto the slide (asshown in FIG. 12 b). In a preferred embodiment, one of the longitudinaledges of the coverglass falls onto the slide. As shown at block 176, thehead assembly is moved downward. In one embodiment, the head assembly ismoved downward while only one edge of the coverglass touches the slide.In this manner, the edge opposite to the edge that touches the slide ismoved proximate to the slide (e.g., between 60 to 100 thousandths of aninch from the surface of the slide) without touching the slide. Thismovement of the head assembly (and in turn the coverglass) downward mayreduce the possibility of breakage of the coverglass and of trapping airbubbles underneath the coverglass. After the head assembly is moveddownward, the spacer arm(s) may be moved, as shown at block 178. In thismanner, the edge previously held by the spacer arm(s) is dropped ontothe slide. In an alternative embodiment, after one edge of thecoverglass is dropped onto the slide, the edge held by the spacer arm(s)may be dropped, bypassing the step of moving the head assembly downward.The head assembly is then moved upward, as shown at block 180

Referring to FIGS. 11 a-d, there is shown a side view of one method ofselecting a coverglass. In one embodiment, a stack 182 of coverglassesmay be raised to the sealing member 72 by a motor 92. The motor 92 mayrun for a fixed period of time, thereby stalling when the stack 182comes into contact with the support block 50. After the sealing member72 couples with the top coverglass of the stack 182, the stack 182 maybe lowered by the motor. To lower the stack 182, the motor 92 is run inreverse. In an alternate embodiment, the stack of coverglasses mayremain stationary and the support block 50 is moved to contact thestack.

As shown in FIG. 11 a, the coverglass is selected by suctioning it fromthe stack 182 of coverglasses. The top coverglass of stack 182 contactssealing member 72. The coverglass preferably contacts at least a portionof sealing member 72, preferably over the entire sealing member 72. Theseal may extend all the way to the perimeter of the coverglass. Thesupports 74 keep the sealing member 72 flat to reduce the possibility ofconcave cupping. Preferably, the suctioning mechanism (e.g., the vacuumpump) can be turned on after the sealing member 72 comes into contactwith the stack 182. In an alternative embodiment, the suctioningmechanism can be turned on prior to contact with the stack 182. Aftercontacting the sealing member 72, the spring member(s) 76 becomecompressed and store potential spring energy.

As shown in FIG. 11 b, after selecting a coverglass 68, the flexiblebacking plate 64 and the sealing member 72 exert a force along one axisof the coverglass 68, and in one embodiment, the long axis of thecoverglass 68 to slightly bend it at a constant radius to separate itfrom any clinging coverglasses 188 that may be sticking to thecoverglass 68 selected. This is in contrast to prior art devices thatexert a force on each end of the coverglass 68. This force is applied byraising the brackets 66 on each side of the support block 50. Thebrackets 66 and the flexible backing plate 64 move creating a flexbending action. The flex bending action causes the top coverglass topeel away from other coverglasses in the stack. Since the seal mayextend to the outer perimeter of the coverglass, a greater bending maybe achieved at the outer edges of the coverglass during separationwithout overstressing the material. This is in contrast to certaindevices in the prior art which use suction mechanisms to apply a greatamount of bending moment in the middle of the coverglass (and a lesseramount of force on the edges of the coverglass).

The coverglass 68 may take on a smooth curved shape due to the equal (ornear equal) bending action taking place. The coverglass 68 will receivean equal amount of stress applied over the entire area of the coverglass68 because of the seal formed between the sealing member 72 and thecoverglass 68. Bending the top glass on the stack 182 to separate itfrom the stack 182 is a reliable method of separating the coverglasses.Another embodiment may have the flexible backing plate 64 using atwisting action to instigate the release of sticking coverglasses. Anymethod of temporarily reshaping the coverglass 68 will assist in theseparation process.

To further increase the chances of a reliable separation, the bentcoverglass is passed through curved upper surface 128 (also shown inFIGS. 8 a and 8 b). The curved upper surface 128 acts as a matched (ornear-matched) curved barrier for the coverglass thereby bumping againstany clinging coverglasses 188. As shown in FIGS. 11 c and 11 d, thecurved upper surface 128 used to wipe underneath the support block 50 ispreferably matched to the shape of the bent or twisted coverglass.Another embodiment may have the curved upper surface 128 pass underneaththe fixed support block 50. FIG. 11 c shows a first orientation for aclinging coverglass 188 to stick onto the selected coverglass 68. FIG.11 d shows a second orientation for a clinging coverglass 188 to stickonto the selected coverglass 68. The matched curved barrier, representedby the side profile of the curved upper surface 128 in the figures,would reject these clinging coverglasses 188 as shown in FIGS. 11 c and11 d, when the sealing member assembly is rotated away from the stack182. This wiping action removes any clinging coverglasses 188, andplaces those coverglasses clinging to the selected coverglass back ontothe remaining stack 182 for future selection.

A side profile of the curved upper surface 128 which is shown in FIG. 11c and FIG. 11 d may take on a different shape so as to match the shapeof the temporarily reshaped coverglass 68. The selected coverglass ispassed close enough to the curved upper surface 128 to remove anyclinging coverglasses 188. Another embodiment may have the wiping actiontaking place underneath the support block 50 with a motor driven devicematching the shape of the temporarily reshaped coverglass.

Referring to FIG. 12 a-c, there is shown a side view of a method ofreleasing the coverglass onto a slide. In one aspect, bonding fluid isplaced on one portion of the slide by bonding fluid nozzles 54, as shownin FIG. 3. As previously mentioned, the bonding fluid may be a gluesolvent, in a preferred embodiment, or glue. Pre-glued coverslips aredisclosed in co-pending application Ser. No. 09/716,344 (Crouch et al.,incorporated herein by reference in its entirety. A first edge of thecoverglass is released onto the portion of the slide where the bondingfluid is placed so that the coverglass forms a “V” shape relative to theslide (see FIG. 12 b). Thereafter, a second edge, opposite the first, ofthe coverglass is released (or forced downward) to cover the slide (seeFIG. 12 c). In this manner, one can minimize the number of gas bubblestrapped underneath the coverglass.

Initially, the specimen is prepared by applying bonding fluid onto theslide. The bonding fluid is preferably applied on the surface of theslide at or near one of the longitudinal edges of the slide. In oneembodiment, four or five discrete drops of bonding fluid may be applied.Alternatively, a bead of bonding fluid along the longitudinal edge maybe applied. The placement of the coverglass in the relative position tothe slide may be accomplished by moving either the support block 50,moving the slide 190, or a combination of both. In a preferredembodiment, the slide 190 remains stationary. The coverglass is thendropped onto the slide, with one of the coverglass's edges touching theslide. This may be performed by turning off the vacuum pump and allowinggravity to carry an edge of the coverglass onto the slide. In apreferred embodiment, the longitudinal edge of the coverglass is droppedonto the slide. In one embodiment, an external device, such as a hook(see e.g., spacer arm 32 in FIG. 3), may be used to drop one edge of thecoverglass onto the slide. In an alternative embodiment, the supportblock 50 may be pivoted so that, while the coverglass is still beingheld by the support block 50, an edge of the coverglass 68 may belowered to the slide 190.

FIG. 12 a shows the support block 50 with a coverglass 68 in thedispensing position. A spacer arm 32 is placed between one edge of thecoverglass 68 and the slide 190. The spacer arm 32 may be pivotallyattached to the sealing member assembly so that it pivots away from theassembly when it is in a down position. The spacer arm 32 acts as a hookwhich catches one end of the coverglass 68 as the vacuum is removed. Thespacer arm 32 is a bar, preferably of metal, which is less than 0.25″wide. In a preferred embodiment, the spacer arm 32 may be pivotallyconnected to the sealing member assembly. After placement of the spacerarm 32, the suctioning mechanism is turned off allowing the coverglass68 to fall freely via gravity as mentioned earlier, and with the forceexerted by the spring member(s) 76, the coverglass 68 may be pushed awayfrom the sealing member assembly.

One embodiment of the mounting of the spring member(s) 76 is to placeone near each corner of the flexible backing plate 64 within theperimeter of the sealing member 72 as shown in FIG. 5. Alternatively,the spring member(s) 76 may be placed outside of the perimeter of thesealing member 72. The preferred embodiment comprises four springmembers 76, one spring member 76 placed near each corner of the sealingmember 72, but alternative embodiments may contain more or fewer springmembers 76. The spring member(s) 76 are compressed when the coverglass68 is suctioned to the sealing member 72. Upon release of the coverglass68 via turning off the vacuum generator, the spring member(s) 76 exert arestoring force to the coverglass 68 pushing it away from the sealingmember 72 and allowing it to fall or be drawn onto the slide 190. Thisinsures the disengagement of the coverglass 68 from the sealing member72.

The spring member(s) 76 may be of a conical, or spherical shape andcomprise a resilient elastomeric material. In the preferred embodiment,four spring members 76 of a conical shape are placed at the corners ofthe sealing member 72. All four spring members 76 exert a force onto thecoverglass 68, due to the buildup of potential spring energy, at or nearthe same instant of time. The conical spring member(s) 76 preferablytake on a cone shape, positioned so that the tip of the cone contactsthe coverglass 68, and the base of the cone is mounted inside theperimeter of the sealing member 72 on the underside of the flexiblebacking plate 64. Using the tip of the cone to contact the coverglass 68lowers the surface area between the cone spring member(s) 76 and thecoverglass 68 that will come into contact. This lowers the possibilityof the coverglass 68 sticking to the cones. Preferably, they are weldedonto sealing member 72.

In reference to FIG. 12 b, when the coverglass 68 is released from thesealing member 72, at least one edge of the coverglass 68 will fall andcontact at least one edge of the slide 190, and the other edge of thecoverglass 68 will fall and contact the spacer arm 32. This creates awedge-shaped gap between the slide 190 and the coverglass 68.

As discussed previously, liquid is placed on one portion of the slide sothat the liquid is in the notch or apex of the “V” shape formed by thecoverglass 68 and the slide 190, as shown in FIG. 12 b. Either thelonger or shorter edge of the rectangular shaped coverglass 68 maycontact the slide 190. As discussed in the background of the invention,coverglasses are typically 1″ by 2″. In a preferred embodiment, thelonger edge (2″) of the coverglass is in contact with the slide.Alternatively, contacting the coverglass 68 with the slide 190 may beaccomplished by tilting the support block 50 relative to the slide 190.In this embodiment, no spacer arm 32 would be needed. Furthermore, inthis embodiment, when the coverglass 68 is released from the sealingmember 72, one edge will contact the slide 190 first, creating the wedgeshaped gap discussed earlier. Another embodiment may have the slide 190tilted with respect to the support block 50. Again, in this embodiment,after the coverglass 68 is released from the sealing member 72, one edgeof it will contact the slide 190 first, creating the desiredwedge-shaped gap between the two.

Once the coverglass 68 contacts the slide 190, the head assembly may bemoved downward. In one aspect, the head assembly is moved downward sothat the edge, which is opposite to the edge which first touched theslide, is close, but not touching the slide (e.g., 60-100 thousands ofan inch). Thereafter, the spacer arm 32 may be removed and the supportblock 50 is raised allowing the opposite edge of the coverglass 68 tofall completely onto the slide 190. This is shown in FIG. 12 c. In apreferred embodiment, the spacer arm 32 is removed by either swinging itaway from the support block 50, or pivoting it away. Another embodimentmay have the spacer arm 32 rotate at least 90° to allow the coverglass68 to fall onto the slide 190. In an alternate embodiment, the spacerarm 32 remains stationary while the slide 190 is lowered relative to thesupport block 50 a distance great enough for the coverglass 68 to falloff of the spacer arm 32 and onto the slide 190. When the spacer arm 32is removed, allowing the coverglass 68 to fall freely, the coverglass 68will not be dragged by the spacer arm 32 off of the slide 190 becausethe bonding fluid on the specimen has a retaining force holding thecoverglass 68 in place. In still an alternate embodiment, a mechanicalstop may be placed such that, when the spacer arm 32 is removed, thecoverglass 68 may hit the mechanical stop if the coverglass 68 adheresto spacer arm.

After the first edge of the coverglass 68 has initially contacted thespecimen and bonding fluid on the slide 190, capillary action will pullbonding fluid to the sharp corner of the wedge gap between thecoverglass 68 and the slide 190. The initial three or four discretedrops of bonding fluid will form a continuous bead with no gaps betweenthem. The bonding fluid will act to draw the coverglass and the slidetogether. As the head assembly is moved downward and/or as the releasedcoverglass tilts down onto the specimen, the advancing bonding fluidline pushes air out from underneath the coverglass 68 as the coverglass68 lowers. The movement of the bonding fluid within the spaces betweenthe coverglass 68 and the slide 190 may take place due to the forces ofcapillary action. The final result is the placement of the coverglass 68completely covering the specimen on the slide 190 with little or notrapped air pockets.

An exemplary embodiment of the present invention has been illustratedand described. It will be understood, however, that changes andmodifications may be made to the invention without deviating from thescope of the invention, as defined by the following claims. Further, theclaims should not be read as limited to the described order of elementsunless stated to that effect. Therefore, all embodiments that comewithin the scope and spirit of the following claims and equivalentsthereto are claimed as the invention.

1. A method for automatically removing a coverglass from the top of astack of coverglasses contained within a cartridge, the coverglasshaving edges, the method comprising the steps of: forming a sealproximate to the edges of the coverglass; exerting a force along theproximate seal, uniformly bending the coverglass along a longitudinalaxis to separate the coverglass from the stack of coverglasses; andmoving the bent coverglass away from the cartridge, wherein thecartridge has an upper surface, and the moving of the coverglass awayfrom the cartridge causes any un-separated coverglasses to be dislodgedfrom the bent coverglass by the cartridge upper surface; wherein thestep of forming a seal includes contacting the coverglass with a sealingmember, the sealing member being attached to or integral with a flexiblebacking plate and being composed of an elastomeric material.
 2. Themethod of claim 1, wherein the step of forming a seal includescontacting the coverglass with a sealing member, the sealing memberconsisting of a single sealing member that forms a seal along acircumference of the coverglass.
 3. The method of claim 1, wherein theflexible backing plate includes a conduit connected to a vacuum sourceand wherein the step of forming a seal further includes applying vacuumto the sealing member.
 4. The method of claim 3, wherein the step ofapplying the vacuum is performed after the step of contacting thecoverglass with the sealing member.
 5. The method of claim 1, whereinthe step of uniformly bending the coverglass includes bending thecoverglass at about a constant bend radius.
 6. The method of claim 5,wherein the step of bending the coverglass further includes bending thecoverglass along a long axis such that the distal ends of the long axisof the coverglass approach each other.
 7. The method of claim 1, furthercomprising the step of moving the stack of coverglasses and the removedcoverglass relative to one another.
 8. The method of claim 7, whereinthe stack of coverglass is moved within a cartridge, the cartridgecomprising one or more apertures in the bottom end of the cartridge forallowing entry of a fork to move the stack of coverglasses.
 9. Themethod of claim 1, further comprising automatically dispensing thecoverglass onto a slide.
 10. The method of claim 9, wherein dispensingcomprises the steps of: releasing a first edge of the coverglass totouch a portion of the slide; and releasing a second edge of thecoverglass onto the slide, the second edge being opposite to the firstedge of the coverglass.
 11. The method of claim 10, wherein the step ofreleasing a first edge of the coverglass to touch a portion of the slidecomprises positioning the coverglass so that the coverglass and theslide form a “V” shape.
 12. The method of claim 10 further comprisingthe step of dispensing liquid onto the slide, the step of dispensingliquid being performed prior to the step of releasing the first edge ofthe coverglass to touch a portion of the slide.
 13. The method of claim12, wherein the first edge of the coverglass and the slide intersect toform a line, and wherein the liquid is dispensed proximate to the line.14. The method of claim 10, wherein the coverglass comprises arectangular shape with a 2 shorter sides and 2 longer sides, and whereinthe first edge is one of the 2 longer sides.
 15. The method of claim 10,wherein the coverglass is uniformly bent around the support block bysuction, and wherein the step of releasing the first edge onto the slidecomprises removing the suction so that the first edge of the coverglassdrops onto the slide by gravity.
 16. The method of claim 15, wherein thesupport block includes a spacer arm, and wherein the second edge of thecoverglass is held by the spacer arm after removing the suction.
 17. Themethod of claim 16, wherein the step of releasing the second edge of thecoverglass onto the slide comprises moving the spacer arm so that thesecond edge of the coverglass drops onto the slide by gravity.
 18. Themethod of claim 10, wherein after the step of releasing the first edgeof the coverglass to touch a portion of the slide, the coverglass andslide form a first angle, the first angle being less than 90 degrees,and further comprising the step of moving the support block and sliderelative to one another so that the coverglass and slide form a secondangle, the second angle being less than the first angle, wherein thestep of moving the support block and slide relative to one another isperformed after the step of releasing the first edge of the coverglassbut before the step of releasing the second edge of the coverglass. 19.The method of claim 18, wherein the step of moving the support block andslide relative to one another comprises moving the support blockdownward.